The disclosed technology relates to a unit drawing mechanism for drawing a unit out from a main unit, and to an image recording apparatus for recording an image on a sheet being transported on a sheet transport path.
In electrophotographic image recording apparatus, a sheet is fed from a sheet feeding tray to an image recording section where an image is formed on the sheet. Then the sheet is output to a sheet output tray. A sheet may become jammed on its way on a sheet transport path. A sheet jam is likely to occur particularly in the image recording section. This is because a sheet tends to be curled while undergoing various processes in the image recording section such as: a developer-image transfer process performed by a transfer device; or a fusing process performed by a fusing device.
A sheet jam is also likely to occur in a reversing transport path on which, in duplex image formation (an image is formed on both sides of a sheet), a sheet with an image formed on a first side is reversed and transported back to the image recording section. This is because the duplex image formation involves a sheet passing through many bifurcations of the sheet transport path.
In the event of a sheet jam, image recording apparatus suspend an image forming process until all sheets present on the sheet transport path are removed. JP H09-134050A discloses that a sheet jammed in the image recording section is removed by drawing the image recording section in a forward direction out of the image recording apparatus and opening a side wall or the like of the section to expose the sheet transport path.
The foregoing configuration of the prior art apparatus, however, involves a small level of exposure of a portion of the sheet transport path located in the image recoding section, even with the image recording section drawn out and the side wall opened. Thus, this configuration renders it hard for a user to remove a jammed sheet. In particular, recent image recording apparatus with high functionality have a complex configuration that renders it hard to provide a large space for removing a jammed sheet.
In consecutive image formation that involves a plurality of sheets present on the sheet transport path, a user is necessitated, if only a small level of exposure of sheet transport path is available, to open side walls or the like of different portions of the image recording section in order to check if all the sheets are removed from the sheet transport path.
As a solution to the foregoing problem, a unit drawing mechanism adapted for use in an image recording apparatus has been proposed that includes a first unit and a second unit. The first unit, in which a first path as part of a sheet transport path is positioned, is movable along a forward direction to draw the first unit out of the apparatus. With the first unit drawn out of the apparatus, the second unit is movable along a direction, perpendicular to the forward direction, to draw the second unit out of the first unit. In the second unit, a second path as another part of the sheet transport path is positioned.
The proposed mechanism eliminates the need for provision of a dedicated space for drawing the unit 2 out of the unit 1 along the forward direction, since space for a user to remove a printed sheet also serves as the space for drawing the unit 2 out of the unit 1. Also, the proposed mechanism allows the second unit to be detached from the first unit by being drawn out of the first unit, thereby enabling the first and second paths to have a greater exposed area than in a conventional configuration where the first and second units are integrated in a single unit. Additionally, the second unit is slidably supported by a slide rail assembly.
For improved workability, it is preferable that the unit drawing mechanism has a minimum number of support members for supporting the first unit so that the first unit is movable. In the proposed mechanism, however, detachment of the second unit from the first unit involves a major shift in the center of gravity of the first unit. Therefore, repeated detachment and attachment of the second unit from and to the first unit causes deformation in the supports of the first unit, resulting in a decrease in positioning accuracy of the first and second units with respect to the apparatus. In order to ensure strength, further, it is necessary to provide a sufficient number of supports for the first unit.
Furthermore, the proposed mechanism is not provided with means for securing the second unit to the first unit so that the second unit does not move. This results in a decreased positioning accuracy of the second unit with respect to the first unit. This also may cause undesirable movement of the second unit drawn out of the first unit.
In light of the foregoing, a non-limiting feature of the disclosed technology provides a unit drawing mechanism with a simple configuration that maintains a high level of positioning accuracy of a first and a second units with respect to an apparatus provided therewith, that ensures a high level of positioning accuracy of the second unit with respect to the first unit by securing the second unit to the first unit so that the second unit does not move, and that prevents undesirable movement of the second unit drawn out of the first unit.